This invention relates to hacksaws and more particularly to portable power hacksaws.
To make a hacksaw blade replaceable, the prior art has generally employed a blade having several holes through which a corresponding number of threaded pins, affixed to a shaft from the motor, pass. A cover and fastening nuts, applied and removed using a wrench, complete the assembly.
Hacksaws in industry are usually mounted in clamps or jigs and used repetitively to saw workpieces one after another. To replace the blade typically means removing the hacksaw from its clamp or jig and then removing a cumbersome holding device; production is decreased. Overtorqued nuts and pin threads strip, requiring nut replacement and in some cases replacement of the hacksaw shaft, further delaying production.
Pin mounted blades tend to contain a fair degree of slop due to the tolerances which are allowed on the sizing of the pins and pin holes in the haft of the blade, thus tending to increase vibration stress in the blade and to increase the tendency of the blade to loosen its nuts or possibly to break.